I've been experimenting lately with using both the Stealth and Notice skills in Showdown. The results have been pretty interesting so far.
Mostly, I use them as opposed rolls when one unit wants to sneak up on another. When a unit is activated, it can make a Notice roll as one of its actions. This is generally a group roll and it has the limitations that it can't be used if the unit intends to run.
Stealth has the same limitation in that the unit that wishes to make a stealthy approach makes a group roll.
There are obviously situations where a group is not going to get to make a stealth roll like when they're crossing an open field in broad daylight. This adds some more tactical options to an already good game.

Fair enough question. Here's an example of how both skills can be used.

Unit A has drawn a King and elects to go on hold. Unit X has drawn a 7 and wants to move to better cover on his activation. Unit X makes an Opposed Roll using their Stealth skill vs Unit A's Notice. If Unit X wins, they get to make their move without Unit A being able to come off hold and fire at them. If Unit A wins, then they can come off hold and open up.
Hope this explains it.

It helps explain it, but now I start thinking "Well, I'll just never go on hold, I'll shoot people while I still know where they are."

Maybe a better use of the Stealth skill (or rather, clearer definition) would be:

A unit with the Stealth Special Ability may elect to move at 1/2 Pace and attempt Stealth.

They roll Agility. Their opponent rolls Smarts. If they succeed, the Stealthy unit is not considered to be in line of sight.

Stealth is not useable within 5" of an opponent.

Something like that? Clearer? I'd also vote for Stealth to be a Special Ability worth 20 points rather than a Skill. It's a pretty potent ability the way you're describing it, and at most a d12 in a Skill is worth 15 points._________________Proud Savagepedia contributor.

This is something we're working on for the Comendium. Due to the complications of mid-game Stealth use, it doesn't appear in the Core Rules. If you guys come up with house rules that work for your game until then, by all means run with them!

Things to keep in mind:

Smarts replaces Notice in Showdown, so you don't have to buy a seperate skill.

Even if the Stealthy troops aren't in line of sight, do you allow dropping a burst template attack on them via an indirect-fire weapon?

Again, even if I don't know their location technically (by the rules), your opponent likely knows it empirically by observing the board. How do you prevent him from taking actions based on this knowledge?

(These are just for your consideration if you want to implement a Stealth skill troop in your games--sort of rheotorical questions. I'm working on some solutions, but haven't come up with one yet that makes me completely happy.) _________________John Goff

A completely different option is to allow stealth rolls to improve the cover safe the unit gets. I would say cant move, but improve cover safe for success a raise means the enemy canīt shoot at the unit at all. Hiding is a action so it incurs a penalty to any other action.
Trying to spot a unit is free if you try to attack the same unit. Ever success and raise reduces the effect of the stealth roll.
If you want a unit to be able to hide in plain sight, so to speak, since the battlefield has more debris then shown you could allow using the cover gained from being prone for this.

Units with Stealth roll their Agility before the battle. If they succeed, they may set their units up after the opponent has set up, and they may set up anywhere on the board outside their opponent's Line of Sight.

Units with Stealth also had access to some unique Edges, like being able to roll their Stealth to improve the level of their cover, being able to roll Agility to gain the Drop on their opponents, or other such things.

John's comments are my basic issues with stealth on the tabletop - I can see the figure, so it's hard not to command my troops to decide that barrel would be much improved with a grenade barrage._________________Proud Savagepedia contributor.

A trick I've seen used in some games for Stealth is to have a number of dummy markers or bases, with a concealed mark (on the bottom, say) that indicates whether it's real or false. (I think the first place I saw this method was in WEG's original Star Wars miniatures game, but I could be wrong.)

When a unit goes into Stealth mode, its position is replaced two or more markers. One is genuine, all others are false. When that unit activates, all of the markers can move (normally spreading out). If a stealth marker gets too close to an enemy unit or gets caught in an area effect, its status will be revealed. If the unit takes a combat action (or virtually any action other than moving), the genuine marker is revealed. Whenever the genuine marker is revealed, all false ones are removed and the unit is returned to the table with the lead figure on the marker and all others formed up behind it.

To implement in Showdown, I would have the unit get one genuine marker and one false marker for success and each raise. A unit can test a stealth marker that is within (Smarts)" (although whether this should be automatic or an opposed Smarts vs Stealth roll, I don't know) to see if it's the real thing.

I haven't had a chance to implement this in my Zombie Showdown games yet, but whenever I do, I'll let y'all know if it works out as planned._________________You can't save the world without kicking a few old ladies down the stairs.

Bhikku - I've used that exact dummy marker mechanic to great effect in a infiltration scenario set at night. The defending player was stretched thin attempting to ID every marker before their (secret) goals were achieved.

I also ran a game (A besieged outpost during a Martian sandstorm) where one player introduced new units to the table with a group of three mystery markers representing them, these were revealed using similar rules to the ones you suggest. It kept the outpost defenders guessing which side the next attack would come from.

Worked a treat in both cases.

I got the idea from the '0' blips from the old editions of Space hulk

I like your idea for successes and raises, introduces a little more variety - I just gave the unit 2 markers if they made a successful stealth roll.

Ran a Weird Wars skirmish over last summer where stealth was the brit's main defensive strategy...

We tried "stealth on the deployment" for an ambush scenario...
models with stealth were allowed to make a Stealth check to conceal 2 models under a "blip" marker.... (as above)
the mods we used were:
1. A successful check allowed the player to deploy 1 blip for each rank of their skill (so a d8 got 3 blips) these could be put up to 8" past the normal deployment
2. each raise either earned an extra blip, or an extra 8" of deployment range.

Sadly, a WC had their stealth explode and it got a little ridiculous, so caps are needed...

for regular stealth, we used a flat roll for stealth that made a difficulty for another model to roll against to "spot" the model for any targeting (an action was spent to spot, but if successful, the model got to shoot without penalty)
again, exploding dice made this a little over powered, Opposed works better.

for the most part, what we found was most effective/fair was:

1. Model declares stealth movement (so no running/shooting) must pass Stealth roll, and is flagged as "stealth"
2. Models attempting to target the stealth model make Opposed check. Success means they can attack, but at a -1 in addition to other modifiers.. a raise negates the -1..._________________I believe Socrates said it best at, "I drank what?"